Conventional grooved rotors for discs and clutches are known in the art. Conventional grooved bands have a distribution of grooves that are generally not optimal for achieving an optimal mean coefficient of friction or for balancing the stresses on the pads and thus eliminating the vibrations induced in the disc and in the pad by their interaction during the braking operation.
In such conventional braking bands, the expression “principal direction of rotation of the disc” defines the direction of rotation corresponding to forward movement of the vehicle. An axis lying in a plane perpendicular to the axis of rotation of the braking band and intersecting the axis of rotation is referred to as a “radial direction”. An axis tangential to a circle lying in a plane perpendicular to the axis of rotation of the braking band and having a point on the axis of rotation at its centre is referred to as a “tangential direction”. The circle defines a circumferential direction of the disc.